Disclaimer: I do not own Leverage nor am I associated with Dean Devlin, Timothy Hutton or Gina Bellman. No copyright infringement is intended.
Perception
Way back then, Nate saw her as a pretty, lustful thief with no sense of morality and no sense of pride.
Time passed and he came to see her as a dignified woman who, though still lustful, was far more beautiful than pretty.
More time passed and she had plenty of pride and plenty of morality, she just liked being able to pick and choose when it was convenient to use them.
Tick tock and she was the love of his life, just out of reach, torturing him that he couldn't have her, due to his own damn sense of morality.